Vehicle fuel management system

ABSTRACT

An integrated fuel management system and method for controlling the fuel storage and delivery in a vehicle. The fuel management system includes a fuel storage tank for storing fuel in a vehicle, a vapor collection canister located within the fuel storage tank, a vent actuator coupled to the vapor collection canister for venting gas from the canister during a vent operation, and a purge actuator is coupled to the vapor collection canister for purging fuel vapor from the vapor collection canister during a purge operation. A variable speed fuel pump is disposed within the fuel storage tank for delivering fuel to a fuel delivery line for an engine. The fuel management system has a controller provided in a module disposed in communication with the fuel for controlling the amount of fuel pumped with the variable speed fuel pump to deliver fuel to the fuel delivery line and further controlling the purge and vent actuators.

This is a divisional of Ser. No. 10/157,363 filed May 29, 2002 now U.S.Pat. No. 6,877,488

BACKGROUND OF THE INVENTION

The present invention generally relates to on-board fuel storage anddelivery to an engine in a vehicle and, more particularly, relates tovehicle fuel management for controlling fuel storage and delivery to theengine.

Automotive vehicles are typically powered by an internal combustionengine that converts the chemical energy of a fuel (e.g., gasoline) tomechanical energy for driving a powertrain which, in turn, propels thevehicle via road wheels. Additionally, some of the mechanical energy isalso converted to electrical energy via an alternator and is stored in abattery and used to power various electrically operated devices.Vehicles are being equipped with increasing numbers of electricallypowered devices, all of which consume energy. Thus, it is desirable toenhance the efficiency of the electrically powered devices in order tomaximize the overall energy efficiency of the vehicle.

Automotive vehicles employ a fuel storage tank and a fuel deliverysystem that delivers a controlled amount of fuel from the fuel storagetank to one or more fuel rails having fuel injectors for dispensing thefuel into the internal combustion engine. At the engine, the fuelinjectors inject a controlled mixture of the fuel and air into theindividual engine cylinders. Many conventional fuel delivery systemstypically employ a single speed on/off fuel pump for pumping pressurizedfuel from the fuel storage tank to the fuel rail which, in turn,supplies the pressurized fuel to the individual fuel injectors. The fuelpump is powered by an electric motor that is operated such that themotor is either off (de-energized) to provide no pumping action or themotor is on (energized) to pump fuel at a fixed pumping speed. The fueloutput from the pump flows through a mechanical regulator that regulatesthe amount of fuel delivered to the fuel rail at a predeterminedpressure. Pumped fuel that is not delivered to the fuel rail is returnedto the fuel storage tank via a return path from the mechanicalregulator.

Many conventional fuel delivery system fuel pumps are continuouslyoperated at a fixed speed as long as the ignition key is in the onposition, regardless of the engine fuel demands. The fuel pump generatesan audible noise when energized at the normal fixed speed. This resultsin a continuous audible noise which can be noticeable to vehicleoccupants, particularly when the engine is operated at low engine loaddemands, e.g., engine idle speed. Continued full speed operation of thefuel pump further consumes electrical energy, which could otherwise bemade available elsewhere to enhance the vehicle energy efficiency.Additionally, the return of a large amount of excessive fuel through theregulator to the fuel storage tank may cause heating of the fuel that,in turn, creates unwanted gas vapor, which adds to evaporativeemissions, and which then must be vented through a charcoal canister.Reducing the fuel pump speed reduces the vapor, which reduces theemissions to reduce the global warming and ozone depletion potentialscaused by the fuel vapors.

Fuel delivery systems have been proposed that employ a variable speedfuel pump electrically controlled to increase and decrease pump speed.One example of a fuel delivery system is disclosed in U.S. Pat. No.4,926,829, entitled “PRESSURE-RESPONSIVE FUEL DELIVERY SYSTEM.” The fueldelivery system described in the aforementioned patent employs apressure regulator in a fuel return line, and a pressure sensor formonitoring pressure in the return line. The fuel pump is energized atlow or high levels depending on the fuel back-pressure in the returnline. Many such fuel delivery systems are generally complex and costly.It is desirable to provide for a fuel delivery system having reducedcomplexity and cost.

Mounted within the fuel storage tank is a carbon (e.g., charcoal)canister for collecting fuel vapor to reduce evaporated emissions. Thevapor collection canister has a fuel vapor vent for venting pressurizedgas from within the fuel storage tank, and also has a fuel vapor purgeactuator for purging the collected fuel vapor from the vapor collectioncanister for burning in the engine. The fuel vapor vent and purgeactuator are periodically operated in response to command controlsignals generated by the engine control module. The fuel collectioncanister is typically periodically purged, without regard to measuringthe actual amount of fuel vapors collected therein. During a fuel filloperation, for example, when the fuel storage tank is excessively filledwith fuel, the fuel canister may rapidly become saturated, hencerequiring a purge operation. The fuel fill tube leading to the fuel tankgenerally includes a mechanical float valve which shuts off theconventional fuel fill dispensing nozzle upon reaching a predeterminedfuel tank pressure. However, it is possible to continue to dispenseincremental amounts of fuel in the fuel storage tank, thereby leading tosaturation of the vapor collection canister.

The conventional fuel pump motor is generally controlled (on or off) inresponse to a command signal received from the vehicle engine controlmodule (ECM) (a/k/a, engine control unit) which performs a multitude ofvehicle functions generally related to engine operation. The enginecontrol module also controls other devices related to the storage anddelivery of fuel to the engine by outputting on/off command signals tovarious devices to control the individual devices. Conventional fueldelivery systems rely primarily upon the engine control module tocontrol the various fuel storage, delivery, and management functions bycontrolling such devices on and off, but do not provide for optimalintegration of fuel delivery functions.

Accordingly, it is therefore desirable to provide for a fuel managementsystem that overcomes deficiencies of prior known vehicle systems forcontrolling the fuel storage and delivery of fuel to the engine on thevehicle. In particular, it is desirable to provide for an integratedsystem of managing fuel storage and delivery within a vehicle. It isalso desirable to provide for a cost affordable fuel delivery systemthat provides enhanced energy efficiency, reduced audible noise, andreduced wiring. It is further desirable to provide for a fuel deliverysystem that offers enhanced fuel management integration including, butnot limited to, fuel tank vent, fuel vapor purge and fuel filloperations.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an integrated fuelmanagement system and method are provided that offer cost affordablecontrols for controlling the fuel storage and delivery in a vehicle. Thefuel management system includes a fuel storage tank for storing fuel ina vehicle, and a vapor collection canister coupled to the fuel storagetank for collecting fuel vapor. A vent actuator is coupled to the vaporcollection canister for venting gas from the canister during a ventoperation. A purge actuator is also coupled to the vapor collectioncanister for purging fuel vapor from the vapor collection canisterduring a purge operation. A variable speed fuel pump is disposed withinthe fuel storage tank for delivering fuel to a fuel delivery line. Thefuel management system further includes a controller provided in amodule disposed in fluid communication with the fuel. The controllercontrols the amount of fuel pumped with the variable speed fuel pump todeliver fuel to the fuel delivery line, and further controls the purgeand vent actuators to perform the purge and vent operations.

According to another aspect of the present invention, a fuel deliverysystem is provided for delivering fuel from a storage tank to a fuelrail of an engine in a vehicle. The fuel delivery system includes avariable speed fuel pump for pumping fuel from a storage tank to a fueldelivery line coupled to a fuel rail. The fuel pump has a variable speedelectric motor operable at multiple speeds. The fuel delivery systemalso includes a sensor for monitoring a load demand characteristic ofthe vehicle. The fuel delivery system further includes a controller forcontrolling the speed of the electric motor as a function of themonitored characteristic. The controller commands a first motor speedduring a sensed high load demand characteristic and further commands asecond lower motor speed during sensed low load demand characteristic.

According to a further aspect of the present invention, a fuel deliverysystem for delivering fuel from a storage tank to a fuel delivery linefor an engine in a vehicle is provided. The fuel delivery systemincludes a variable speed fuel pump for pumping fuel from a storage tankto a fuel delivery line. The fuel pump includes a variable speedelectric motor operable at variable speeds. The fuel delivery systemfurther includes a return line in fluid communication with the fluiddelivery line, and a flow sensor for sensing the flow rate of fuelthrough the return line. A controller controls the speed of the electricmotor as a function of the sensed flow rate.

According to yet a further aspect of the present invention, a fuel fillsystem and method are provided for controlling the fuel filling of afuel storage tank. The fuel fill system includes a vapor collectioncanister coupled to the fuel storage tank for collecting evaporated fuelvapor. A vent actuator is coupled to the fuel storage tank for ventinggas from the fuel storage tank during a vent operation. A purge actuatoris coupled to the vapor collection canister for purging fuel vapor fromthe vapor collection canister during a purge operation. A controllercontrols the vent actuator and purge actuator, and further controls thevent actuator during a fuel fill operation to control the dispensing offuel into the fuel storage tank.

Yet, a further aspect of the present invention includes a method ofventing gas from within a fuel storage tank of a vehicle comprising thesteps of sensing an internal pressure within the fuel storage tank, andcontrolling a vent actuator as a function of the sensed internalpressure. Another aspect of the present invention includes a method ofsensing a vehicle accident and turning off fuel delivery when a vehicleaccident is sensed.

These and other features, advantages and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic diagram shown in partial cross-sectional viewillustrating a vehicle fuel management system according to a firstembodiment of the present invention;

FIG. 2 is a block diagram further illustrating the vehicle fuelmanagement system of FIG. 1;

FIG. 3 is a flow diagram illustrating a control routine for controllingfuel delivery based on sensed pressure with the fuel management system;

FIG. 4 is a flow diagram illustrating a control routine for controllingfuel delivery based on sensed engine throttle position with the fuelmanagement system;

FIG. 5 is a schematic diagram illustrating a vehicle fuel managementsystem according to a second embodiment;

FIG. 6 is a block/flow diagram illustrating fuel delivery of the fuelmanagement system according to the embodiment of FIG. 5;

FIG. 7 is a schematic diagram illustrating a vehicle fuel managementsystem according to a third embodiment;

FIG. 8 is a block/flow diagram illustrating fuel delivery of the fuelmanagement system according to the embodiment of FIG. 7;

FIG. 9 is a cross-sectional view of one embodiment of a flow sensoremployed in the fuel management system of FIG. 7;

FIG. 10 is a cross-sectional view of another embodiment of a flow sensoremployed in the fuel management system of FIG. 7;

FIG. 11 is a schematic diagram illustrating a vehicle fuel managementsystem according to a fourth embodiment;

FIG. 12 is a block/flow diagram illustrating fuel delivery of the fuelmanagement system according to the embodiment of FIG. 11;

FIG. 13 is a schematic diagram illustrating a vehicle fuel managementsystem according to a fifth embodiment;

FIG. 14 is a block/flow diagram illustrating fuel delivery of the fuelmanagement system according to the embodiment of FIG. 13;

FIG. 15 is a block/flow diagram further illustrating the fuel vaporpurge and vent functions of the fuel management system;

FIG. 16 is a flow diagram illustrating a vent control routine forcontrolling the fuel vapor vent actuator for venting vapor from the fuelstorage tank;

FIG. 17 is a flow diagram illustrating a purge control routine forcontrolling the fuel vapor purge actuator for purging fuel vapor fromthe fuel collection canister;

FIGS. 18A and 18B is a flow diagram illustrating a fuel fill controlroutine for controlling the fuel fill operation; and

FIG. 19 is a flow diagram illustrating a routine of controlling enginefuel injection based on the sensed fuel composition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a first embodiment of the vehicle fuel managementsystem 10 is generally illustrated for use in on-board management andcontrol of fuel for an engine in an automotive vehicle. The vehicle fuelmanagement system 10 integrates various fuel related functions generallyassociated with the fill, storage, and delivery of fuel to the engine inan automotive vehicle. The vehicle fuel management system 10 includes afuel delivery system for delivering fuel from a fuel storage tank 12 toa fuel rail 64 associated with the vehicle engine. The vehicle fuelmanagement system 10 also controls the fuel fill operation to fill andstore fuel in the fuel storage tank 12. Further, the fuel managementsystem 10 controls the fuel vapor vent and purge operations to ventpressurized gas and purge evaporated vapor emissions from a fuelcollection canister, respectively. The various fuel related functionsperformed by the fuel management system 10 are integrated together andare adapted to be controlled locally to provide for a cost affordable,adaptive, and efficient fuel management system.

The fuel storage tank 12 defines a contained volume for storing fuel(e.g., gasoline) that is made available for delivery to the vehicleengine. Disposed within the fuel storage tank 12 is a fuel reservoirassembly 14 which contains a fuel filter 16 and a fuel pump 18. The fuelreservoir assembly 14 is located at or near the bottom wall of tank 12so that it is substantially submerged in the fuel when a sufficientsupply of fuel is present. The fuel reservoir assembly 14 is arranged sothat fuel passes via inlets into the reservoir assembly 14 from thesurrounding fuel storage tank 12. The fuel pump 18 has a pump outlet 20which, in turn, is connected to a fuel delivery line 26. Also shown is afuel return line 22 located on pump outlet 20. A non-contact fuelpressure sensor 24 is coupled to the fuel return line 22 for measuringfuel pressure in the return line 22. The fuel pump 18 draws a controlledamount of fuel from the fuel reservoir assembly 14 through the fuelfilter 16 to produce pressurized fuel in the pump outlet 20 and, thus,in the fuel delivery line 26 to control module 40 is connected to fuelpump 18. In combination, this creates the variable speed control.

According to the first embodiment, a fuel control module (FCM) 40 ismounted to the outside of fuel reservoir assembly 14 so that the module40 is substantially positioned at or near the bottom wall of tank 12and, thus, module 40 is likewise submerged in the stored fuel. Fuelcontrol module 40 contains various electronic devices commonly housedwithin and/or connected to a housing having cooling fins 50 which serveto cool the fuel control module 40 and its associated electronics viathermal conduction with the fuel contained within the fuel storage tank12. The cooling fins 50 are thermally conductive (e.g., aluminum) andare disposed in a heat transfer relationship with the module 40electronics and the surrounding fuel to transfer thermal energy awayfrom the module 40 and its electronics.

The fuel control module 40 is shown containing a non-contact fuel levelsensor 42 for measuring the fuel level within the fuel storage tank 12.Fuel level sensor 42 may include a piezo sensor. An inertia switch 46 isalso provided in fuel control module 40 for sensing inertia due todynamic movement. Inertia switch 46 may include an acceleration sensorfor detecting acceleration indicative of a vehicle collision. Theinertia switch 46 serves as a local sensing mechanism to detect avehicle collision so that corrective action may be taken to control fuelstorage and delivery during the detected collision. For example, thefuel pump 18 may be shut off upon the inertia switch 46 detecting avehicle collision or other vehicle accident. The fuel control module 40further includes a fuel temperature sensor 44 for measuring temperatureof the fuel within the fuel storage tank 12. Extending through a seal 49in the fuel reservoir assembly 14 is a fuel composition sensor 48 forsensing the composition of the fuel to be delivered to the engine. Thesensed fuel composition may include sensing the presence of additivessuch as alcohol and ethanol to provide flex fuel sensing. By determiningthe sensed composition of the fuel, the fuel control module 40 notifiesthe engine control module of changes in the fuel composition that mayrequire altering of engine operating parameters to enhance the operationof the engine. The fuel control module 40 further includes amicroprocessor-based controller in communication with the varioussensors and control devices for controlling various aspects of the fuelmanagement system 10, as explained herein.

Mounted to the inside top wall of fuel storage tank 12 is a carbon vaporcollection canister 32 for collecting fuel vapor within the fuel storagetank 12. Fuel vapor collection canister 32 may include a carbon (e.g.,charcoal) material as is commonly known in the art for collectingevaporative emissions fuel vapors to allow for venting of the fuelstorage tank 12. The fuel vapor collection canister 32 is shownconnected to a fuel vapor vent actuator 34 and a fuel vapor purgeactuator 36. The fuel vapor vent actuator 34 is an electromechanicalvalve which allows for venting to occur between the outside atmosphereand the inside volume of the fuel storage tank 12. When relievingpressure from within fuel storage tank 12, the vented gases are passedthrough the vapor collection canister 32 so that the evaporated gasvapors are collected and thus are not discharged into the surroundingatmosphere. The fuel vapor purge actuator 36 is an electromechanicalvalve that controls the purge operation to purge collected fuel vaporfrom within the vapor collection canister 32. During a fuel vapor purgeoperation, the collected fuel vapor trapped within the canister 32 ispurged and sent to the vehicle engine, where the purged fuel vapor isburned to dispose of the fuel vapor with reduced emissions. The fuelvapor purge actuator 36 and fuel vapor vent actuator 34 are locallycontrolled by the fuel control module 40 in accordance with the presentinvention. The fuel vapor vent actuator 34 is controllable to controlthe pressure within the fuel storage tank 12, which allows for controlof the fuel fill operation. The need for a purge operation is monitoredby the fuel control module 40, and a purge operation can be requested bythe fuel control module 40 based on the need for a purge operation.

Formed within the top wall of fuel storage tank 12 is an opening 28which is sealed closed with a cap assembly 30. Prior to installing thecap assembly 30, the fuel reservoir assembly 14, with fuel deliverycontrol 40 attached thereto, is inserted into the fuel storage tank 14.By providing a single opening in the fuel storage tank 12, variouscomponents of the fuel delivery system may be easily installed withinthe fuel storage tank 12 through a single opening formed within the fuelstorage tank 12 to accommodate the fuel fill inlet, fuel deliveryoutlet, and electrical wire connections between the inside and outsideof the fuel storage tank 12. The cap assembly 30 includes a fuel flowoutlet 61 in fluid communication with the fuel delivery line 26 fordelivering fuel from the fuel delivery line 26 to a chassis fuel line60. The chassis fuel line 60 is connected to the fuel rail 64 generallylocated at the engine of the vehicle. The fuel rail 64 includes aplurality of fuel injectors 66 for injecting fuel into the correspondingcylinders of the internal combustion engine (not shown). A pressuresensor 62 is located at the inlet of the fuel rail 64 to measurepressure of fuel supplied to the fuel rail 64.

The cap assembly 30 also includes a fuel fill inlet 57 in fluidcommunication with the fuel storage tank 12 and the fuel fill tube 56which leads to a fuel fill inlet 72 generally located on the outside ofthe vehicle. The fuel fill inlet 72 is configured to receive a fuel filldispensing nozzle (not shown) at a refueling station to allow fuel to bedispensed within the fuel storage tank 12. A fuel neck sensor 70 isprovided near the fuel fill inlet 72 to sense the presence of a fuelfill dispensing nozzle so as to detect an anticipated fuel filloperation. Disposed within the fuel fill tube 56 is a electromechanicalvalve 58 for opening and closing the fuel flow passage through the fuelfill tube 56. The electromechanical valve 58 is an electricallycontrolled, normally closed valve that prevents fuel flow through fuelfill tube 56. Electromechanical valve 58 is controlled in response to acontrol command signal received from the fuel control module 40. Uponsensing insertion of a fuel fill dispensing nozzle into the fuel fillinlet 72 of fuel fill tube 56 via fuel neck sensor 70, fuel controlmodule 40 commands electromechanical valve 58 to open to allow fuel tobe dispensed through fuel fill tube 56 and inlet 57 into the fuelstorage tank 12. When the fuel fill dispensing nozzle is removed fromthe fuel fill inlet 72, as detected by fuel neck sensor 70, fuel controlmodule 40 commands the valve 58 to close to prevent fluid flow throughfuel fill tube 56. Additionally, the electromechanical valve 58 alsoserves to prevent leakage of fuel from the fuel storage tank 12 throughthe fuel fill tube 56, particularly during a vehicle rollover event, avehicle collision, or other vehicle accidents. By providing anelectrically controlled valve 58, the flow of fuel through the fuel filltube 56 can thus be controlled.

Mounted to the cap assembly 30 is an electrical connector 54 generallyhaving a plurality of electrical pin connectors. Electrical connector 54includes a signal line that connects to a communication bus (not shown)which allows data communication with other devices within the vehicle,including the engine control module. The communication bus may includeany of a number of known vehicle communication buses. Alternately, thecommunication bus may include one or more dedicated communication linesfor communicating with one or more devices located elsewhere in thevehicle. The electrical connector 54 is also connected to a plurality ofsignal lines, generally shown by line 38, which extend into the fuelstorage tank 12 and connect to the fuel control module 40. Outside offuel storage tank 12, electrical connector 54 is connected to theelectromechanical valve 58, pressure sensor 62, and fuel neck sensor 70.Electrical connector 54 is further connected to the fuel vapor purgeactuator 36 and vent actuator 34 for controlling actuation of thecorresponding purge and vent devices, as is explained later hereinafter.Vent actuator 34 and purge actuator 36 may communicate with fuel controlmodule 40 either directly within the fuel tank 12 or by way of connector54 (as shown).

The fuel control module 40 is shown in FIG. 2 in communication withvarious devices of the fuel management system 10. The fuel controlmodule 40 includes a microprocessor-based controller having amicroprocessor 76 and memory 78. The controller hardware including themicroprocessor 76 may include a commercially available controller havingsufficient processing capability to process the programmed routines.Fuel management control routines are stored in memory 78 and areprocessed by the microprocessor 76 to perform fuel storage and deliveryfunctions as described herein. The fuel control module 40 receives aninput from the throttle position sensor 74 which provides an indicationof the demand for engine load and changes to engine load. By monitoringthe engine throttle position, an anticipated change in fuel demand canbe determined so that the amount of fuel delivered to the fuel rail 64is timely controlled. Fuel control module 40 also receives signals fromthe fuel rail pressure sensor 62, the fuel tank vacuum pressure sensor52, the fuel level sensor 42, the fill neck sensor 70, the pressuresensor 24, inertial switch 46, and fuel composition sensor 48. The fuelcontrol module 40 generates output signals including a fuel pump speedcontrol voltage signal (V_(m)) for controlling the speed of a variablespeed electric motor 80 driving the fuel pump 18. In addition, the fuelcontrol module 40 generates output signals to control the fuel vaporvent solenoid (actuator) 34 and the fuel purge solenoid (actuator) 36.The fuel control module 40 further provides an output control signal tocontrol actuation of the fuel fill tube mounted electromechanical valve58.

The fuel control module 40 is an adaptive local controller that provideslocal control of the fuel management system 10. Fuel control module 40also communicates with the engine control module (ECM) 82 via a serialdata communication bus 84. Fuel control module 40 communicates serialdata containing information including control command signals, sharedsensor signals, and diagnostic information with the engine controlmodule 82. In addition, the fuel control module 40 may furthercommunicate with the engine control module 82 via one or more dedicatedsignal lines, such as lines 86 and 88 shown communicating the fuel leveloutput and the fuel composition signals, respectively. It should beappreciated that a shared data communication bus and/or any number ofdedicated signal lines may be connected between the fuel control module40 and the engine control module 82 to communicate data therebetween.

Referring to FIG. 3, one embodiment of a control routine 200 performedby fuel control module 40 for controlling the fuel delivery system ofthe fuel management system 10 according to the first embodiment of FIGS.1 and 2 is illustrated therein. The fuel delivery control routine 200begins at step 202 and proceeds to step 204 to measure the fuel railpressure via the rail pressure sensor 62. The pressure sensor 62provides an indication of the fuel pressure supplied to the fuel rail64. The fuel delivery control routine 200, via the fuel control module40, monitors the fuel rail pressure and controls the speed of thevariable speed fuel pump 18 so as to maintain a predetermined fuelpressure at the fuel rail 64. In decision step 206, the fuel controlmodule 40 determines how much fuel is required to maintain thepredetermined fuel pressure at the fuel rail. If less fuel is requiredto maintain the predetermined rail pressure, fuel delivery controlroutine 200 proceeds to decision step 208 to check if the fuel controlmodule 40 has determined the receipt of a valid command and, if so, thefuel control module 40 decreases the pump motor control voltage V_(m) todecrease the fuel flow in step 216, and then completes the routine 200in step 222. If the fuel control module 40 determines that more fuel isrequired to maintain the predetermined rail pressure, control routine200 proceeds to decision step 212 to check if the fuel control module 40has determined receipt of a valid command and, if so, the fuel controlmodule 40 increases the pump motor control voltage V_(m) to increasefuel flow, and then completes the routine 200 at step 222. If the fuelcontrol module 40 determines that the fuel requirements have not changedin order to maintain the predetermined rail pressure, fuel deliverycontrol routine 200 proceeds to decision step 210 to check if the fuelcontrol module 40 has determined receipt of a valid command and, if so,the fuel control module 40 commands the same (unchanged) pump motorcontrol voltage V_(m) so that the fuel flow remains the same, beforeending control routine 200 at step 222. If the fuel control module 40determines that the received command is not valid in any of steps 208,210, or 212, control routine 20Q proceeds to step 214 so that the fuelcontrol module 40 turns off the pump motor control voltage V_(m) to stopthe fuel flow, and then control routine 200 ends at step 222.

Accordingly, the fuel control module 40 monitors the fuel rail pressureand determines the amount of fuel required to maintain a predeterminedrail pressure. If the fuel rail pressure decreases, the fuel controlmodule 40 requests an increase in the pump motor control voltage V_(m)to increase the speed of the fuel pump. Contrarily, if the fuel railpressure increases, the fuel control module 40 decreases the pump motorcontrol voltage V_(m) to decrease fuel flow to the fuel rail 64 tomaintain the predetermined rail pressure. It should be appreciated thatthe change in the pump motor control voltage V_(m) may be achieved witha small predetermined increment, or may be varied in differentincrements, in order to accurately meet the fuel rail pressurerequirements to maintain the predetermined fuel rail pressure. The fueldelivery control routine 200 is repeated fast enough such that smallincremental changes in the motor voltage V_(m) may add up to largechanges in a very short period of time (e.g., 15 ms). It should beappreciated that the fuel control module 40 monitors the fuel railpressure and provides the variable speed fuel pump control to maintainthe predetermined rail pressure, substantially independent of the enginecontrol module 82. As a consequence, the fuel delivery may be controlledlocally at the fuel control module 40, thereby relaxing the processingrequirements of the engine control module 82.

Another embodiment of a fuel delivery control routine 230 is shown inFIG. 4 for controlling the fuel pump 18 based on the sensed enginethrottle position. The fuel delivery control routine 230 begins at step232 and proceeds to step 234 to measure the engine throttle position assensed by the throttle position sensor 74. The engine throttle positionprovides an indication of the anticipated load demanded by the engine,and thus the anticipated fuel injection requirements. In decision step236, the engine control module (ECM) 82 determines how much fuel isrequired to meet the engine requirements for the measured throttleposition. If the throttle position changes, the engine control module 82can anticipate the increase or decrease in the amount of fuel that isrequired to supply sufficient fuel to the fuel rail 64. If the enginecontrol module 82 determines that less fuel is required, the enginecontrol module 82 sends a command signal to the fuel control module 40to reduce the fuel flow in step 238. Thereafter, in step 244, the fuelcontrol module 40 determines if a valid command is received and, if so,decreases the pump motor control voltage V_(m) to decrease fuel flow. Ifthe engine control module 82 determines that more fuel is required basedon the measured throttle position, the engine control module 82 sends acommand signal to the fuel control module 40 to increase the fuel flowin step 242. Thereafter, the fuel control module 40 determines if avalid command is received and, if so, increases the pump motor controlvoltage V_(m) to increase fuel flow in step 256. If the engine controlmodule 82 determines that the same fuel is required, the engine controlmodule 82 maintains the same fuel control command to the fuel controlmodule 40. Thereafter, the fuel control module 40 determines if a validcommand is received and, if so, maintains the same pump motor controlvoltage V_(m) so that the fuel flow remains the same. If the fuelcontrol module 40 determines that a valid command has not been receivedin any of steps 244, 246, or 248, the fuel control module 40 turns offthe pump motor control voltage V_(m) to end fuel flow in step 250,before ending the control routine 230 in step 258.

Accordingly, the fuel delivery control routine 230 monitors throttleposition of the engine and anticipates the fuel demand of the engine sothat fuel delivery can be adjusted to meet the anticipated demand. Inparticular, the engine control module 82 instructs the fuel controlmodule 40 to vary the speed of the fuel pump 18 to increase or decreasethe amount of fuel delivered to the fuel rail 64 as a function of thechange in the monitored throttle position. By adjusting the fuelpressure at the fuel rail 64 based on throttle position, the fueldelivery control routine 230 is able to quickly adapt to anticipatedengine load changes, thus minimizing any fuel delivery delay which mayotherwise occur.

A second embodiment of the fuel management system 10 is illustrated inFIGS. 5 and 6 with the fuel control module 40 mounted to the fuelreservoir assembly 14, absent the return path 22 and pressure sensor 24shown in the first embodiment. The fuel management system 10 of thesecond embodiment has no return path for returning fuel back into thefuel reservoir assembly 14, and thus is a returnless fuel deliverysystem. Instead, the fuel that is pumped into the pump outlet 20 ispassed through both fuel delivery line 26 and chassis line 60 and issupplied to the fuel rail 64.

As shown in FIG. 6, the fuel rail pressure sensed at the fuel rail 64via pressure sensor 62 is provided as an input to the engine controlmodule 82. The engine control module 82 generates a pulse-widthmodulated (PWM) output command signal via control logic 90 andtransistor 92 that is communicated as a command signal to the fuelcontrol module 40. The engine control module 82 has a microprocessor andmemory containing the control logic 90 which is generally configured toexecute control routines for controlling functions related to thevehicle engine. For example, the engine control module 82 controls theinjection of fuel and air into the engine cylinders via the fuelinjectors 66. In addition, the engine control module 82 may process thesensed fuel rail pressure and generate a pulse-width modulated (PWM)control output signal to instruct the fuel control module 40 to controlthe speed of the fuel pump 18. Alternately, the fuel rail pressure maybe directly input into the fuel control module 40 or may be communicatedto the fuel control module 40 via the engine control module 82 so thatthe fuel control module 40 generates the motor control signal to controlthe speed of the fuel pump 18.

The fuel control module 40 includes control logic 100 containing controlroutines for controlling various functions of the fuel management system10. The control logic 100 receives the pulse-width modulated signal viaan engine control module input monitor 108 on line 94. Control logic 100converts the pulse-width modulated command control signal to a DC outputvoltage V_(m). According to one example, the fuel control module 40converts the pulse-width modulated command signal to a voltage V_(m) inthe range of 4.5 volts to 12.8 volts.

The fuel control module 40 also receives the vehicle ignition voltage(e.g., +14 volts) via a high-side drive 102, while a low-side drive 104is coupled between ground and the low side of the motor 80. Pump motorcontrol voltage V_(m) is applied to the high-side drive 102, while thelow-side drive 104 is grounded. By employing both high-side and low-sidedrives 102 and 104, the fuel control module 40 is able to electricallyisolate and disconnect each of the high and low sides of the pump motor80 for safety and protection in the event that an electrical failureoccurs. A motor fault detect block 112 detects faults of the motor 80, adriver fault detect block 114 detects faults of the motor drive, and adiagnostics report 110 is generated by the fuel control module 40 and iscommunicated to the engine control module 82. The fuel control module 40is able to provide diagnostic monitoring of the variable speed fuel pumpand the local devices, and to communicate the monitored information inthe diagnostics report 110 to the engine control module 82. This enableslocalized diagnostic testing to occur, such as checking for leakagewithin the fuel storage tank 12. By providing local diagnostics testing,fuel management processing requirements of the engine control module 82are thus reduced, thereby leaving processing capability of enginecontrol module 82 available for other operations in the vehicle.

In operation, the engine control module 82 monitors the fuel railpressure at the fuel rail 64 and adjusts the pulse-width modulated inputsignal to provide closed loop monitoring of the fuel system pressure.With the ignition voltage applied to the fuel control module 40 and theengine control module 82 providing a pulse-width modulated commandsignal indicative of fuel flow requirements of the system, the fuelcontrol module 40 generates and supplies the motor control voltage V_(m)to the fuel pump motor 80 to command a desired speed of the motor 80.The spinning action of the fuel pump draws fuel from the fuel reservoir14 through the fuel filter 16 at the required flow rate and pressure. Inthis embodiment, no mechanical pressure regulator is used to control thefuel pressure at the pump outlet. Instead, the closed loop monitoring bythe engine control module 82 of pressure at the fuel rail 64 is used tocommand the fuel control module 40 to adjust the speed of the fuel pumpmotor 80 to compensate for changes in fuel pressure that may occur. Theoutput drive of the fuel control module 40 is linear and thereforeproduces low electromagnetic interference (EMI) noise as compared to apulse-width modulated motor drive arrangement. While a DC voltage drivehas been described herein, it should be appreciated that alternativedrivers, such as pulse-width modulated drive signals, may be employed tocontrol the speed of the pump motor 80.

Referring to FIG. 7, the fuel management system 10 is shown according toa third embodiment of the present invention. In the third embodiment,the fuel control module 40 is integrated within the cap assembly 30outside of the fuel storage tank 12, and a pressure regulator 120 isintegrally formed in the cap assembly 30. The pressure regulator 120 hasan inlet connected to the variable speed pump 18 for receiving thepumped fuel in line 26. The pressure regulator 120 regulates the amountof pressurized fuel applied to the fuel rail 60 via the fuel deliveryline 60. Pressure regulator 120 has a fuel return line 122 which returnsregulated fuel supplied by fuel pump 18 that is not passed on to chassisfuel line 60. The fuel return line 122 integrally extends within thehousing of fuel control module 40 and extends within cap assembly 30 andinto fuel reservoir assembly 14. With the fuel return line 122 extendingthrough fuel control module 40, the returned fuel is in heat transferrelationship with fuel control module 40 to serve as a cooling medium tocool the fuel control module 40 and its associated electronics.Accordingly, the fuel control module 40 may be mounted outside of thefuel storage tank 12 and may likewise be cooled by the fuel to preventoverheating of the electronics and thus allow for a reduced package sizefuel control module 40.

It should be appreciated that the pressure regulator 120 regulates theamount of fuel pressure supplied to the fuel chassis line 60 and fuelrail 64, despite the difference in fuel pressure generated by thevariable speed fuel pump 18, which is varied in speed to meet thedemands of the engine. The return line 122 further extends through aflow sensor 124 for monitoring the flow rate of returned fuel in line122. The flow sensor 124 may be separate from or integrally formedwithin the fuel control module 40. By sensing return flow rate of fuelthrough line 122, the fuel pump 18 may be varied based on the sensedflow rate. Alternately, it should be appreciated that the fuel pump 18may be controlled based on other parameters as described hereinincluding the rail pressure as sensed by pressure sensor 62, and theengine throttle position.

The fuel delivery system shown in FIG. 7 is further illustrated in FIG.8. As shown, the fuel return line 122 of pressure regulator 120 returnsfuel to the fuel reservoir assembly 14. The fuel return line 122 has aknown constant cross-sectional area. Fluid flowing through the fuelreturn line 122 is monitored by the flow sensor 124 which senses theflow rate of the fluid through return line 122. By maintaining aconstant flow rate through return line 122, a constant fuel pressure canbe achieved at the fuel rail 64. Fuel control module 40 receives themeasured flow signal and generates a motor control signal V_(m) tocontrol the speed of the variable speed pump motor 80 to maintain adesired fuel flow rate through fuel return line 122.

The fuel control module 40 includes a high-side drive 102 for receivingthe ignition voltage and a low-side drive 104 coupled to ground. Motorfault detect block 112 provides fault detection to the control logic100. The fuel control module 40 may share serial data with the enginecontrol module 82 via serial data bus 84. The serial data may includeparameters related to the engine and other devices within the vehicle.In addition, diagnostic ports may be sent from the fuel control module40 to the engine control module 82 via the serial data bus 84. The fuelcontrol module 40 receives command signals from the engine controlmodule 82 which are used in emergency situations such as vehiclerollover, crank timeout, and vehicle collision to command the fuelcontrol module 40 to shut down the fuel pump 18.

During normal operation, the fuel control module 40 monitors the fuelflow rate through return line 122 as sensed by flow sensor 124 andcontrols the speed of the fuel pump motor 80 to provide accurate fueldelivery to the fuel rail 60. With the ignition voltage applied, thefuel control module 40 provides a linear output signal to the fuel pumpmotor 80 based on monitored fuel flow rate which causes the motor 80 andpump 18 to spin and pump fuel to the pressure regulator 120. The use ofa high-side drive 102 and a low-side drive 104 allows the fuel controlmodule 40 to electrically isolate or disconnect each side of the pumpmotor 80, which offers safety and protection in the event of anelectrical failure. While high-side and low-side drives 102 and 104 areshown, it should be appreciated that one of the high-side or low-sidedrives 102 and 104 alone may be employed. The spinning action of thefuel pump 18 draws fuel from the reservoir 14 through the fuel filter16, at a pressure corresponding to the fuel flow rate. When changes infuel flow rate occur, the fuel control module 40 senses such changes andcompensates by adjusting the linear output voltage V_(m) to the motor 80to maintain the system flow rate. If fuel pressure is higher than therequired system pressure, the pressure regulator 120 causes the fuel tobe bypassed through the fuel return line 122 to the reservoir 14. Theoutput drive of the fuel control module 40 is linear and thereforeproduces low electromagnetic interference (EMI) noise. It should beappreciated that alternative drivers, such as a peak pulse-widthmodulated driver, may be employed to control the speed of the pump motor80.

Referring to FIG. 9, the flow sensor 124 is shown configured accordingto a first embodiment. The flow sensor 24 is a Hall-effect sensoremploying a moveable valve assembly 502 having a magnet 504 and a spring506 biasing the valve assembly 502 in one direction. The valve assembly502 is disposed in a fluid path defined by housing 508 between an inlet500 and an output 510 which completes the flow path that returns fuel tothe fuel storage tank via outlet 510. A sensing element 516 senses thedisplacement of the magnet 504 within valve assembly 502 which moveswithin housing 508 as a function of the fuel flow. The flow sensor 124is shown integrally formed and sealed within cap assembly 40.Additionally, the flow sensor 124 includes a power device 514 (e.g.,MOSFET) and is formed of an aluminum housing 512 that is thermallyconductive to provide heat transfer relationship between the fuel flowin the return path and the electronic devices, such as power device 514,to remove heat from the electronic devices. As engine fuel demandchanges, the integrated fuel delivery system optimizes fuel flow. Thefuel flow may be continuously adjusted to deliver the lowest optimalfuel flow and the lowest system power. As engine fuel consumptionincreases, the bypass flow decreases and the valve assembly 502 beginsto move. The electronic control detects the sensed movement of the valveassembly 502 and increases motor power to return the valve assembly 502to a designated bypass flow set point. As engine fuel consumptiondecreases, increased bypass flow is sensed, and the electronic controldecreases motor power to return the valve assembly 502 to the designatedbypass flow set point. It should be appreciated that the fuel flow isbypassed internally to prevent high pressure from occurring at the inletof the sensor assembly.

The flow sensor 24 can be integrated electrically with the fuel deliverysystem motor control and other sensor and control electronics to providea complete vehicle fuel management control system for the regulation offuel delivery to the engine. In the first embodiment shown, when no fuelflow is present in the flow sensor 124, the inlet side of the flowsensor valve assembly 502 is forced against the sensor housing 508 byspring 506. As fuel flow increases in the inlet, the valve assembly 502is forced forward by the force of the fluid flow passing over the valveassembly 502 to complete fuel flow through the outlet 510. The spring506 biasing of the valve assembly 502 is compressed to maintain a forceagainst the back side of the valve assembly 502 that is equal to theforce applied to the front surface, and as the flow increases, the valveassembly 502 is forced back further, thus further compressing the spring506.

Referring to FIG. 10, a flow sensor 124′ is shown according to a secondembodiment. The flow sensor 124′ is shown having a vertically disposedvalve assembly 502 which has a mass that experiences a force (weight)downward due to gravity. As the fuel flow increases, the fuel flowforces the valve assembly 502 upwards within the vertical cylinder, thusallowing more fuel to pass through to the outlet 510. In addition, thefuel acts as a lubricant on the sides of the valve assembly 502. Thus,the vertical arrangement of the valve assembly 502 provides a selflubricating embodiment which may also utilize weight of the valveassembly and thus reduces the bias force required by spring 506. It isalso possible to eliminate the spring 506, according to this embodiment.

Accordingly, the flow sensor 124 or 124′ provides a Hall-effect flowsensor for sensing fuel flow through the return path in a vehicle fueldelivery system for use in controlling the speed of the variable speedfuel pump. The flow sensor 124 or 124′ provides an analog or discretedigital output signals indicative of the amount of fuel flow through thereturn path. It should be realized that the travel distance of the valveassembly 502 may be limited to a small distance of 0.25 inch and thesensor may have a flow rate in the range of zero (0) to one hundredfifty (150) liters per hour, according to one example. The flow sensor124 or 124′ and corresponding electronics are in heat transferrelationship with the fuel so as to utilize the fuel in the fuel tank tocool the active electronics, and thus the fuel is advantageously used asa heat sink.

A fourth embodiment of the fuel management system 10 showing yet afurther fuel delivery system is illustrated in FIGS. 11 and 12. In FIG.11, the fuel management system 10 is shown having the fuel controlmodule 40 disposed within the fuel storage tank 12 and connected to thefuel reservoir assembly 14. In this embodiment, the outlet 20 of thevariable speed fuel pump 18 is configured to pass through a flow path 45provided internal to the fuel control module 14 which, in turn, isconnected to the fuel delivery line 26. Disposed in communication withthe internal flow path 45 and module 40 is the flow sensor 124 (see FIG.12) integrally mounted within the fuel control module 40. The flowsensor 124 monitors the rate of flow of fuel through flow passage 45internal to the fuel control module 40. Accordingly, by employing a flowsensor 124 internal to fuel control module 40, a reduction in the wiresand external components is achieved.

Referring particularly to FIG. 12, the fourth embodiment of the fuelmanagement system 10 operates so that the fuel pump 18 pumps fuelthrough outlet 20 into flow path 45, to fuel delivery line 26, and thento the fuel rail 64. The flow sensor 124 generates an output flow signalthat is processed by the fuel control module 40 and is used to controlthe speed of the variable speed pump motor 80, as explained above.

A fifth embodiment of the fuel management system 10 is illustrated inFIGS. 13 and 14. Referring particularly to FIG. 13, a pressure regulator24 is disposed within the fuel reservoir assembly 14 connected to theoutlet 20 of variable speed fuel pump 18. Pressure regulator 24regulates the pressure of fuel in line 26 and provides a return fluidflow path 22 to return fuel back into reservoir 14. Also shown is thefuel control module 40 mounted external to the fuel storage tank 12.According to this embodiment, the fuel control module 40 could belocated anywhere in the vehicle.

With particular reference to FIG. 14, the pressure regulator 24 isfurther shown providing the return flow path 22 back to reservoir 14.The variable speed pump motor 80 is driven at a speed commanded by thefuel control module 40 to command the fuel pump 18 to draw fuel throughfilter 16 to the pressure regulator 24 via pump outlet 20. The pressureregulator 24 regulates the pressure of the fuel supplied to the fuelrail 64 and returns the remaining fuel to the reservoir 14. The fuelcontrol module 40 receives a pulse-width modulated duty cycle commandsignal from the engine control module 82. The fuel control module 40calculates the proper motor control signal based on the engine controlmodule 82 input of a pulse-width modulated command duty cycle. The fuelcontrol module 40 also provides to the engine control module 82diagnostics report 110. In this embodiment, the fuel control module 40regulates the speed of the fuel pump motor 80 by pulse-width modulatingthe motor pump output via internal low side drive circuitry 130 causingthe pump motor 80 and pump 18 to spin at a desired speed. The spinningaction of the pump motor 80 and pump 18 draws fuel from the reservoir 14through a fuel filter 16, thus producing a fuel pressure just above therequired system pressure. The system fuel pressure is maintained usingan in-line mechanical pressure regulator 24. If the fuel pressure ishigher than the required system pressure, the pressure regulator 24causes fuel to be bypassed from the system back into the reservoir 14via return flow line 22. According to this embodiment, the fuel controlmodule 40 controls the speed of the fuel pump motor 80 to provide acontrolled amount of fuel flow at a pressure just above what is actuallydemanded by the vehicle engine. This allows the pressure regulator 24 tomaintain fuel pressure while producing minimal bypass flow through flowline 22. According to this configuration, the life of the fuel pumpmotor 80 may be extended by allowing it to operate at a reduced speed,when less fuel is demanded by the engine. In addition, lower audiblenoise is generated by the fuel system, particularly at vehicle idle,less heating of the fuel is achieved, and lower power is consumed by thefuel pump motor 80, particularly when the engine fuel demands are low.

The fuel control module 40 further controls fuel venting, vapor purging,and fuel fill operations, and may control other functions related to thefuel management system 10. Referring to FIG. 15, the vapor collectioncanister 32 is shown within the fuel storage tank 12 communicating withthe fuel vapor vent solenoid 34 and the vapor purge solenoid 36. Thefuel vapor vent solenoid 34 is controlled in response to a commandsignal generated by the fuel control module 40 to open the fuel vaporvent solenoid 34 to allow gas to escape through an air filter 132 to theoutside atmosphere, or vice versa. The fuel control module 40 likewisecontrols the vapor purge solenoid 36 to open the vapor purge solenoid 36during a purge operation to allow the collected vapors be sent to theengine throttle body 132 for burning in the engine. In controlling thevent and purge operations, the fuel control module 40 receives variousinputs including a tank pressure signal from the vacuum/pressure sensor52, a fuel level signal from a fuel level sensor 42, and the fuelcomposition signal from the fuel composition sensor 48. The fuel controlmodule 40 also controls and monitors the state of the fuel fill necksensor 70 to further control the fuel fill operation.

Referring to FIG. 16, a vent control routine 300 that may be performedby fuel control module 40 for controlling the vent operation to maintaina desired pressure within the fuel storage tank 12 is illustratedtherein. Beginning at step 302, the vent control routine 300 proceeds tomeasure the fuel tank pressure via the vacuum/pressure sensor (52) instep 304. In decision step 306, the measured fuel tank pressure iscompared to a high-pressure limit and, if the fuel tank pressure doesnot exceed or equal the high-pressure limit, the vent control routine300 ends at step 318. If the measured fuel tank pressure exceeds or isequal to the high-pressure limit, the vent control routine 300 proceedsto measure the fuel level in step 308, to calculate the volume of thevapor to be vented in step 310, and then commands opening of the airvent valve in step 311. With the air vent valve open, decision step 312determines whether the fuel tank pressure remains higher than thehigh-pressure limit and, if so, continues to monitor this comparison indecision step 312 with the vent open. When the engine is operating andconsuming fuel, the air vent valve is open to prevent a lack of airflowinto the fuel storage tank so as to prevent a vacuum lock conditionwhich could stall the engine. In addition, the air vent valve can becontrolled to open and close to regulate the amount of air and gascoming into the fuel tank and escaping from the fuel tank. Once themeasured fuel tank pressure is no longer greater than the high-pressurelimit, vent control routine 300 proceeds to step 314 to close the airvent valve, and then records the volume of the vapor that was vented instep 316, before ending in step 318. Accordingly, the fuel controlmodule 40 accurately controls the amount of vapor that is vented fromthe fuel storage tank 12 to relieve the fuel storage tank 12 ofexcessive pressure buildup.

Referring to FIG. 17, a purge control routine 320 that may also beperformed by fuel control module 40 for purging collected vapor from theevaporative emissions vapor collection canister is illustrated therein.Purge control routine 320 begins at step 322 and proceeds to determineif the vapor canister is saturated in decision step 324. The amount ofsaturation of the vapor collection canister can be determined the fuelfill routine and the number of venting cycles. If the vapor collectioncanister is not saturated, the purge control routine 320 ends at step336. If the vapor collection canister is determined to be saturated,purge control routine 320 proceeds to decision step 326 to determine ifthe engine conditions are right for a purge operation. The right engineconditions for purge may include sufficient engine temperature, enginespeed (RPM), elapsed time period elapsed from last purge, and time sincevehicle start. If the right engine conditions for canister purge are notmet, the purge control routine 320 proceeds to close the purge valve instep 334 and then ends in step 336.

If the right engine conditions for purge are met, the purge controlroutine 320 proceeds to open the purge valve in step 328 and thenmonitors the active purge time in step 330. Next, decision step 332monitors whether the purge time is complete and, if not, continues tomonitor the purge conditions and keep the purge valve open until thepurge time is complete. Once the purge time is complete, purge controlroutine 320 proceeds to step 334 to close the purge valve and then endsat step 336. Accordingly, the fuel control module 40 is able to controlthe purge operation of the vehicle. However, the purge operation mayrequire one or more command signals from the engine control module 82 todetermine when the engine conditions are satisfied for a purgeoperation. It should also be appreciated that the fuel control module 40may coordinate with the engine control module 82 such that either theengine control module 82 and/or fuel control module controls the purgeoperation.

Referring to FIGS. 18A and 18B, a fuel fill control routine 340 that maybe performed by the fuel control module 40 is illustrated forcontrolling the fuel fill operation for dispensing fuel into the fuelstorage tank 12. The fuel fill control routine 340 begins at step 342and proceeds to decision step 344 to determine if the fuel filler neckis open, which is indicative of a fuel fill dispensing nozzle beingdisposed within the fuel filler neck. The presence of the dispensingnozzle is sensed via the fuel fill sensor 70. If the fuel filler neck isnot open, the fuel fill sequence ends at step 382. Accordingly, the fillcontrol routine 340 may disallow the fuel fill operation to continue ifthe presence of a fuel fill dispensing nozzle is not detected. If thefuel filler neck is determined to be open, the fuel fill control routine340 proceeds to step 346 to inhibit the fuel pump operation. Next, instep 348, the control routine 340 measures the initial fuel tank levelvia the tank level sensor, and, in step 350 stores the measured initialfuel level.

Next, in decision step 352, the fuel fill control routine 340 determineswhether the vehicle system has a filler neck and, if so, first performsa fuel vapor vent operation in step 354, and then opens the filler neckvalve in step 356. The fuel filler neck is a sensor and valvearrangement that eliminates the need for a fuel cap, as it creates thesealing of the fill tube. If the system does not have a filler neck, thefuel fill control routine 340 determines a set point for the fuel at thefuel level in step 358. Following steps 356 and 358, the fuel fillcontrol routine 340 proceeds to open the air vent valve in step 360, andthen measures the fuel level in step 362.

Proceeding to decision step 364, the fuel fill control routine 340determines if the fuel level is full and, if the fuel level is full,then proceeds to decision step 370 to determine if the system has afiller neck. If the system does not have a filler neck, then fuel fillcontrol routine 340 closes the air vent valve in step 384, increases thefuel level at the full set point in step 386, and then records thenumber of times that the fuel fill level has been reached in step 388,before returning back to step 362. If the system has a filler neck asdetermined in decision step 370, the fuel fill control routine 340proceeds to step 372.

If the fuel level is determined in decision step 364 not to be full, thefuel fill control routine 340 proceeds to check if the filler neck isopen in decision step 366 and, if the neck is open, returns to step 362.If the filler neck is not open, the fuel fill control routine 340 thenchecks for whether the system has a filler neck in decision step 368and, if not, jumps forwards to step 374. If the system does have afiller neck, the fuel fill control routine 340 closes the fill neckvalve first in step 372, before proceeding to step 374.

In step 374, the fuel fill control routine 340 closes the air ventvalve, and then proceeds to calculate the volume of the tank vapor thatwas vented in step 376. The volume of the tank vapor that was vented isthen recorded in step 378. Finally, the final fuel level is stored inmemory in step 380, before ending the fuel fill control routine 340 instep 382. Accordingly, the fuel fill control routine 340 monitors thefuel fill operation and controls the fueling operation to preventexcessive fuel from being dispensed within the fuel storage tank so asto prevent saturation of the fuel collection canister. In doing so, thefuel fill control routine 340 may open and close the vent valve so as tocreate a pressure which causes the fuel fill dispensing nozzle to shutoff. Further, if the fuel dispensing nozzle continues to inject fuelinto the fuel storage tank, the fuel fill control routine 340 monitorsthe continued fuel injection. By monitor the fuel level and thecharacteristics of the fuel fill operation, the fuel control module 40may determine when a purge operation should be performed. This fuelrouting is used to reduce the evaporative emissions, which are createdduring the fueling operation, thus controlling the amount of prefills,but preventing the overfill of the system and venting which canotherwise occur in a manual fuel fill system.

Referring to FIG. 19, a fuel flex sensing control routine 400 isillustrated for sensing the composition of fuel to be injected into theengine and adjusting engine parameters based on the sensed fuelcomposition. The fuel composition sensing routine 400 begins at step 402and proceeds to measure the fuel composition via the fuel compositionsensor in step 404. In step 406, the fuel composition sensing routine400 determines the dielectric constant of the fuel. Decision step 408decides when the determined information is to be processed with the fuelcontrol module 40. If the fuel dielectric constant is to be processed bythe fuel control module 40, routine 400 proceeds to step 410 todetermine the fuel composition at the fuel control module 40. Fuelcomposition information is then sent to the engine control module 82 instep 412. The engine control module 82 adjusts the fuel injector timingand ignition timing as a function of the fuel composition in step 414.Accordingly, the engine may be adjusted to compensate for changes in thecomposition of the fuel, particularly fuel containing various additivessuch as ethanol and alcohol which affect the optimal performance of theengine.

If the dielectric constant is determined in step 408 not to be processedby the fuel control module 40, the fuel dielectric constant is sent tothe engine control module 82 in step 416, so that the engine controlmodule 82 adjusts the fuel injection timing and ignition timing in step414 as a function of the dielectric constant. Accordingly, either thefuel control module 40 or the engine control module 82 may determine thecomposition of the fuel and provide the composition information to theengine control module 82 to adjust engine operation based on the fuelcomposition.

Accordingly, the fuel management system 10 of the present inventionadvantageously provides for an integrated system employing a local fuelcontrol module 40 in communication with various electronic sensors anddevices related to fuel storage and delivery to provide enhanced fuelmanagement on-board a vehicle. The fuel control module providesintegrated control at a local level which lessens the processingcapability required by the engine control module 82. By acquiringinformation local to the fuel storage and delivery system, the fuelcontrol module 40 employs fewer electrical connections between theengine control module 82 and the fuel management related components. Inaddition, the fuel control module 40 advantageously provides for controlof various functions of the vehicle including vent operations, purgeoperations, fuel fill operations, as well as enhanced variable speedfuel pump control.

It will be understood by those who practice the invention and thoseskilled in the art, that various modifications and improvements may bemade to the invention without departing from the spirit of the disclosedconcept. The scope of protection afforded is to be determined by theclaims and by the breadth of interpretation allowed by law.

1. A method of venting gas from within a fuel storage tank of a vehicle, said method comprising the steps of: sensing an internal pressure within the fuel storage tank; controlling a vent actuator as a function of the sensed internal pressure; and determining the volume of vapor vented from the fuel storage tank to a vapor collection canister due to actuation of the vent actuator.
 2. The method as defined in claim 1, wherein the step of controlling the vent actuator comprises processing the sensed internal pressure with a local controller located separate from the engine controller, wherein the local controller generates a signal to control the vent actuator.
 3. A method of venting a fuel storage tank in a vehicle, said method comprising the steps of: sensing a pressure within the fuel storage tank; controlling a vent actuator for venting fuel vapor to a vapor collection canister as a function of the sensed pressure; determining the volume of vapor vented from the fuel storage tank to said vapor collection canister; and pursing the collected fuel vapor from the vapor collection canister based on the volume of vapor so vented for burning in the engine.
 4. The method of claim 1 additionally comprising purging the fuel vapor collected in the vapor collection canister based on the volume of vapor vented into the canister.
 5. The method of claim 4 wherein the purging is performed by burning the vapor in the canister within a vehicle engine. 